1. Field of the Invention
The present invention relates to a speaker system used for, for example, audio equipment.
2. Description of the Related Art
A speaker outputs sound by vibrating a vibrating plate and thus changing the pressure of the surrounding air (sound pressure).
In the case where a single speaker does not provide a sufficient sound pressure, a desired sound pressure can be obtained by synthesizing sounds output from a plurality of speakers.
FIG. 12 is a plan view of a conventional speaker system 1200 including four speakers. The speaker system 1200 includes a first speaker 1201, a second speaker 1202, a third speaker 1203 and a fourth speaker 1204 which are provided on a planar baffle plate 1210.
FIG. 13 is a graph illustrating the relationship between the number of speakers and an increase in sound pressure. The increase in sound pressure is defined as a difference between a synthesized sound pressure from an arbitrary number of speakers and sound pressure output from a single speaker, and is represented in units of dB. The graph shown in FIG. 13 is given by the following theoretical expression, where L is assumed to be 70 dB.             L      p        ⁡          (      a      )        :=            20      ·              log        ⁡                  (                      a            ·                          10                              L                20                                              )                      -    L  
a:=1 . . . 10
L:=70 dB
Table 1 shows specific values given by the above theoretical expression.
As shown in FIG. 13 and Table 1, as the number of speakers increases, the sound pressure increases.
The conventional speaker system 1200 including a plurality of speakers on a planar area has the following problem. When the speaker system is located in a space, for example, in a space within a vehicle, on a wall of a room or on a table, which has a limited surface area, the number of speakers which can be located is limited. As a result, the sound pressure cannot be increased as desired.
A speaker system according to the present invention includes a first speaker; a second speaker; and a first spacer for separating the first speaker and the second speaker from each other so that the first speaker and the second speaker face each other. The first speaker and the second speaker are located so that opposing faces of the first speaker and the second speaker output sounds of an identical phase. The first speaker, the second speaker and the first spacer form a first sound path through which the sounds output from the opposing faces of the first speaker and the second speaker pass.
In one embodiment of the invention, the first sound path is formed so that a transfer direction of the sounds passing through the first sound path is perpendicular to amplitude direction of vibrations of the first speaker and the second speaker.
In one embodiment of the invention, the speaker system further includes at least one baffle plate, which is provided so that the sounds passing through the first sound path is directed to a direction parallel to the amplitude direction of vibrations of the first speaker and the second speaker.
In one embodiment of the invention, the speaker system further includes at least one baffle plate, which is provided so that the sounds passing through the first sound path is directed to a direction perpendicular to the amplitude direction of vibrations of the first speaker and the second speaker.
In one embodiment of the invention, the speaker system further includes a third speaker; and a second spacer for separating the second speaker and the third speaker from each other so that the second speaker and the third speaker face each other. The second speaker and the third speaker are located so that opposing faces of the second speaker and the third speaker output sounds of an identical phase. The second speaker, the third speaker and the second spacer form a second sound path through which the sounds output from the opposing faces of the second speaker and the third is speaker pass.
In one embodiment of the invention, the second sound path is formed so that a transfer direction of the sounds passing through the second sound path is perpendicular to amplitude direction of vibrations of the second speaker and the third speaker.
In one embodiment of the invention, the speaker system further includes at least one baffle plate, which is provided so that the sounds passing through the second sound path is directed to a direction parallel to the amplitude direction of vibrations of the second speaker and the third speaker.
In one embodiment of the invention, the speaker system further includes at least one baffle plate, which is provided so that the sounds passing through the second sound path is directed to a direction perpendicular to the amplitude direction of vibrations of the second speaker and the third speaker.
In one embodiment of the invention, the first sound path and the second sound path are formed so that the transfer direction of the sounds passing through the first sound path and the transfer direction of the sounds passing through the second sound path are opposite to each other.
In one embodiment of the invention, the first speaker and the second speaker have an identical structure; the first speaker and the second speaker are located so that a front face of the first speaker and a front face of the second speaker face each other or so that a rear face of the first speaker and a rear face of the second speaker face each other; and the first speaker and the second speaker are vibrated with an identical phase.
In one embodiment of the invention, the first speaker and the second speaker have an identical structure; the first speaker and the second speaker are located so that a front face of the first speaker and a rear face of the second speaker face each other or so that a rear face of the first speaker and a front face of the second speaker face each other; and the first speaker and the second speaker are vibrated with opposite phase.
In one embodiment of the invention, the first speaker and the second speaker are each a piezoelectric speaker including a piezoelectric element; a polarization direction of the piezoelectric element of the first speaker is opposite to a polarization direction of the piezoelectric element of the second speaker; and a phase of an electric signal input to the first speaker is identical with a phase of an electric signal input to the second speaker.
In one embodiment of the invention, a phase of an electric signal input to the first speaker is opposite to a phase of an electric signal input to the second speaker.
In one embodiment of the invention, the first speaker and the second speaker each include a frame; a vibrating plate; a piezoelectric element provided on the vibrating plate; a damper connected to the frame and the vibrating plate for supporting the vibrating plate so that the vibrating plate is linearly vibratile; and an edge provided so as to fill a gap between the vibrating plate and the frame. The damper acts as an electrode.
In one embodiment of the invention, the first speaker and the second speaker are each a dynamic speaker.
Thus, the invention described herein makes possible the advantages of providing a speaker system for increasing the sound pressure using a plurality of speakers while maintaining the same surface area as that of a single speaker.